1. Field of the Invention
The present invention relates to an image position detector to detect the end position of an image on an image carrier and an image forming device incorporating such an image position detector.
2. Description of the Prior Art
Japanese Patent Application Publication No. 2010-217325 discloses an image forming device to form a position correcting pattern on a paper transfer belt and read this pattern with a sensor to correct an image write timing.
Specifically, such an image forming device forms position correcting patterns for a reference color and for a primary color on the transfer belt and irradiates the patterns with infrared rays with a wavelength having a peak of spectral sensitivity characteristic relative to the primary color pattern, to detect intensity of reflection from the patterns. Then, it sets a threshold for the reflection intensity to find the center of each pattern, calculate a positional shift amount from the centers between the two colors and correct a positional shift on the basis of the calculated shift amount. Further, this device is configured not to generate diffuse rays which would otherwise affect the position detection.